Does passing mean pretending here?

Context:
Mind-control theories from the Korean War era came under criticism in subsequent years. According to forensic psychologist Anthony, the CIA invented the concept of "brainwashing" as a propaganda strategy to undercut communist claims that American POWs in Korean communist camps had voluntarily expressed sympathy for communism. Anthony stated that definitive research demonstrated that fear and duress, not brainwashing, caused western POWs to collaborate. He argued that the books of Edward Hunter (whom he identified as a secret CIA "psychological warfare specialist" passing as a journalist) pushed the CIA brainwashing theory onto the general public. He further asserted that for twenty years, starting in the early 1950s, the CIA and the Defense Department conducted secret research (notably including Project MKULTRA) in an attempt to develop practical brainwashing techniques, and that their attempt failed.[17]
The U.S. military and government laid charges of "brainwashing" in an effort to undermine detailed confessions made by U.S. military personnel to war crimes, including biological warfare, against the Koreans.[18] Frank Schwable, Chief of Staff of the First Marine Air Wing was shot down in North Korea. After Chinese radio broadcasts claimed to quote him admitting to participating in germ warfare, United Nations commander Gen. Mark W. Clark denounced said: "Whether these statements ever passed the lips of these unfortunate men is doubtful. If they did, however, too familiar are the mind-annihilating methods of these Communists in extorting whatever words they want .... The men themselves are not to blame, and they have my deepest sympathy for having been used in this abominable way."[19]